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Connectivity

The „Connectivity“ group is interested in the relevance of fiber tracts for the structure and architecture of the surface and cortex of the brain. A particular focus are changes in the anatomy of the brain’s surface and fiber tracts at older age.

To study the anatomy of the fiber tracts and their relevance for the structural connectivity of the brain, we investigate different organizational levels, from large fiber bundles up to the fanning of these bundles into single fibers in the cortex. This is achieved by combining different in-vivo and post-mortem imaging techniques. We particularly focus on the investigation of connectivity in the posterior part of the brain, i.e. parietal and occipital cortex, for understanding the paths for information processing from the visual system into the multimodal association cortices of the parietal lobe and subsequently, into areas of the frontal lobe. To integrate effects of genetic and environmental influences on connectivity, we use data from large epidemiological population studies with thousands of subjects, to which the “Connectivity” group is contributing (1000BRAINS; German National Cohort) .
The approach of our group for studying brain connectivity allows investigation of the anatomy of fibers and fiber bundles across different scales. Results will be incorporated into the multimodal brain atlas which is developed in the INM-1 (Working group Architecture and Brain Function).

Research focus: Anatomy of fiber bundles

To study large fiber bundles we use novel advanced diffusion imaging techniques in a large cohort of older adults (1000BRAINS), dwhich allow for optimized reconstruction of crossing fiber bundles due to high angular resolution. These high-angular resolution diffusion imaging (HARDI) data are reconstructed using advanced algorithms which are independent from assumptions of classic diffusion tensor imaging, such as constrained spherical deconvolution algorithms. These data are additionally used for extraction of tract-specific quantitative parameters to study white-matter microstructure during aging.
Since resolution of in-vivo diffusion imaging is limited, we additionally include fiber tract reconstructions based on high-resolution post-mortem diffusion imaging (collaboration Dr. Alard Roebroeck; Brain Imaging Center, Universiteit Maastricht, The Netherlands).

Research focus: Cortical fibers

For studying the course of nerve fibers into the cortex, a resolution at the microscopic level is needed, much higher than currently available in MRI settings. We thus use microscopic fiber maps, which are generated based on 3D polarized light imaging (Working Group Fibre Architecture: Polarized Light Imaging). This allows investigation of fiber distributions in cortical layers as well as at the transition from the white matter into the cortex. We are particularly interested in the starting and end points, respectively, of larger and smaller fiber bundles, e.g. U-fibers, as well as in the parcellation of the parietal and occipital cortices into distinct areas based on the distribution of tangentially and radially oriented fibers (collaboration senior professor Prof. Dr. Karl Zilles).